U.S. patent application number 14/049022 was filed with the patent office on 2014-04-10 for method and apparatus for media data delivery control.
This patent application is currently assigned to Samsung Electronics Co., LTD. The applicant listed for this patent is Samsung Electronics Co., LTD. Invention is credited to Kong Posh Bhat, Imed Bouazizi, Youngkwon Lim.
Application Number | 20140098811 14/049022 |
Document ID | / |
Family ID | 50432633 |
Filed Date | 2014-04-10 |
United States Patent
Application |
20140098811 |
Kind Code |
A1 |
Bouazizi; Imed ; et
al. |
April 10, 2014 |
METHOD AND APPARATUS FOR MEDIA DATA DELIVERY CONTROL
Abstract
A method and apparatus control delivery of media data in a
transmission system. A method of operating a sending entity in the
transmission system includes identifying a fixed delay associated
with transmission of media data in the transmission system and
sending information about the fixed delay as a requirement on a
length of time after transmission that the media data is passed to
an application layer component or presented to a user of a
receiving entity. A method of operating a receiving entity in the
transmission system includes receiving media data and information
about a fixed delay associated with the media data and identifying
a requirement on a length of time after transmission that the media
data is passed to an application layer component or presented to a
user from the information about the fixed delay.
Inventors: |
Bouazizi; Imed; (Plano,
TX) ; Lim; Youngkwon; (Plano, TX) ; Bhat; Kong
Posh; (Plano, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Samsung Electronics Co., LTD |
Suwon-si |
|
KR |
|
|
Assignee: |
Samsung Electronics Co.,
LTD
Suwon-si
KR
|
Family ID: |
50432633 |
Appl. No.: |
14/049022 |
Filed: |
October 8, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61712045 |
Oct 10, 2012 |
|
|
|
Current U.S.
Class: |
370/389 |
Current CPC
Class: |
H04L 49/9005 20130101;
H04N 21/4381 20130101; H04L 65/4084 20130101; H04L 65/60 20130101;
H04N 21/44004 20130101; H04N 21/85406 20130101; H04L 65/604
20130101; H04L 65/80 20130101; H04N 21/64322 20130101; H04L 1/0045
20130101; H04L 65/602 20130101 |
Class at
Publication: |
370/389 |
International
Class: |
H04L 29/06 20060101
H04L029/06 |
Claims
1. A method of operating a sending entity in a transmission system,
the method comprising: identifying a fixed delay associated with
transmission of media data in the transmission system; and sending
information about the fixed delay as a requirement on a length of
time after transmission that the media data is passed to an
application layer component or presented to a user of a receiving
entity.
2. The method of claim 1, further comprising: determining a buffer
size requirement for the receiving entity based on the fixed delay
and a bitrate associated with the media data; and sending the
buffer size requirement to the receiving entity in association with
the media data.
3. The method of claim 2, wherein the sending entity is configured
to use a hypothetical receiver buffer model, the fixed delay, and
the buffer size requirement to verify that the transmitted data is
conformant
4. The method of claim 1, wherein identifying the fixed delay
comprises: estimating a transmission delay associated with a
transmission path from the sending entity to one or more receiving
entities in the multi-point transmission system; estimating a
buffering delay associated with processing received packets for the
media data; and calculating the fixed delay based on the
transmission delay and the buffering delay.
5. The method of claim 4, wherein estimating the transmission delay
comprises: estimating a maximum transmission delay based on
transmission media and device types associated with each of the
receiving entities in the multi-point transmission system.
6. The method of claim 4, wherein estimating the buffering delay
comprises: determining whether forward error correction (FEC) is
applied to packets for transmission of the media data; and
including a FEC buffering delay in the estimate of the buffering
delay.
7. A method of operating a receiving entity in a transmission
system, the method comprising: receiving media data and information
about a fixed delay associated with the media data; and identifying
a requirement on a length of time after transmission that the media
data is passed to an application layer component or presented to a
user from the information about the fixed delay.
8. The method of claim 7 further comprising: storing received data
associated with the media data in a buffer until a time from a
transmission timestamp associated with the received data plus the
fixed delay has elapsed; and in response to determining that a
present time is the transmission timestamp associated with the
received data plus the fixed delay, providing the received data to
the user via a user interface.
9. The method of claim 7, wherein the length of time for the fixed
delay is based on an estimate of a transmission delay associated
with a transmission path from a sending entity to one or more
receiving entities in the multi-point transmission system and an
estimate of a buffering delay associated with processing received
packets for the media data.
10. The method of claim 9, wherein the estimate of the transmission
delay includes an estimate of a maximum transmission delay based on
transmission media and device types associated with each of the
receiving entities in the multi-point transmission system.
11. The method of claim 9, wherein the estimate the buffering delay
includes an estimate for a forward error correcting buffering
delay.
12. An apparatus in a sending entity in a transmission system, the
apparatus comprising: a controller configured to identify a fixed
delay associated with transmission of media data in the
transmission system; and a transmitter configured to send
information about the fixed delay as a requirement on a length of
time after transmission that the media data is passed to an
application layer component or presented to a user of a receiving
entity.
13. The apparatus of claim 12, wherein: the controller is
configured to determine a buffer size requirement for the receiving
entity based on the fixed delay and a bitrate associated with the
media data; and the transmitter is configured to sending the buffer
size requirement to the receiving entity in association with the
media data.
14. The apparatus of claim 13, wherein the sending entity is
configured to use a hypothetical receiver buffer model, the fixed
delay, and the buffer size requirement to verify that the
transmitted data is conformant
15. The apparatus of claim 12, wherein the controller is configured
to: estimate a transmission delay associated with a transmission
path from the sending entity to one or more receiving entities in
the multi-point transmission system; estimate a buffering delay
associated with processing received packets for the media data; and
calculate the fixed delay based on the transmission delay and the
buffering delay.
16. The apparatus of claim 15, wherein the controller is configured
to: estimate a maximum transmission delay based on transmission
media and device types associated with each of the receiving
entities in the multi-point transmission system.
17. The apparatus of claim 15, wherein the controller is configured
to: determine whether forward error correction (FEC) is applied to
packets for transmission of the media data; and include a FEC
buffering delay in the estimate of the buffering delay.
18. An apparatus in a receiving entity in a transmission system,
the apparatus comprising: a receiver configured to receive media
data and information about a fixed delay associated with the media
data; and a controller configured to identify a requirement on a
length of time after transmission that the media data is passed to
an application layer component or presented to a user from the
information about the fixed delay.
19. The apparatus of claim 18 further comprising: a memory
configured to store received data associated with the media data in
a buffer until a time from a transmission timestamp associated with
the received data plus the fixed delay has elapsed; and wherein the
controller is configured to provide, in response to determining
that a present time is the transmission timestamp associated with
the received data plus the fixed delay, the received data to the
user via a user interface.
20. The apparatus of claim 18, wherein the length of time for the
fixed delay is based on an estimate of a transmission delay
associated with a transmission path from a sending entity to one or
more receiving entities in the multi-point transmission system and
an estimate of a buffering delay associated with processing
received packets for the media data.
21. The apparatus of claim 20, wherein the estimate of the
transmission delay includes an estimate of a maximum transmission
delay based on transmission media and device types associated with
each of the receiving entities in the multi-point transmission
system.
22. The apparatus of claim 20, wherein the estimate the buffering
delay includes an estimate for a forward error correcting buffering
delay.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S) AND CLAIM OF PRIORITY
[0001] The present application claims priority to U.S. Provisional
Patent Application Ser. No. 61/712,045, filed Oct. 10, 2012,
entitled "METHOD AND APPARATUS FOR MEDIA DATA DELIVERY CONTROL".
The content of the above-identified patent document is incorporated
herein by reference.
TECHNICAL FIELD
[0002] The present application relates generally to media data
delivery in a transmission system and, more specifically, to
control the delivery and presentation of the media data.
BACKGROUND
[0003] Moving Picture Experts Group (MPEG) media transport (MMT) is
a digital container standard or format that specifies technologies
for the delivery of coded media data for multimedia service over
heterogeneous IP network environments. The delivered coded media
data includes both audiovisual media data requiring synchronized
decoding and presentation of a specific unit of data in a
designated time, namely timed data, and other types of data that
are decoded and presented in an arbitrary time based on the context
of service or interaction by the user, namely non-timed data.
[0004] MMT is designed under the assumption that the coded media
data will be delivered through a packet-based delivery network
using Internet Protocols (IPs), such as real-time transport
protocol (RTP), transmission control protocol (TCP), user datagram
protocol (UDP), etc. MMT is also designed with consideration for
characteristics of different delivery environments. For example,
the end-to-end delay of delivery of each packet from a sending
entity to a receiving entity may not always be constant, and the
underlying network providers must provide a way to distinguish
signaling messages from the media data. Accordingly, there is a
need for improved standards in MMT media data delivery.
SUMMARY
[0005] Embodiments of the present disclosure provide a method and
apparatus for controlling delivery of media data in a transmission
system.
[0006] In one exemplary embodiment, a method for operating a
sending entity in the transmission system is provided. The method
includes identifying a fixed delay associated with transmission of
media data in the transmission system. The method also includes
sending information about the fixed delay as a requirement on a
length of time after transmission that the media data is passed to
an application layer component or presented to a user of a
receiving entity.
[0007] In another exemplary embodiment, a method for operating a
receiving entity in the transmission system is provided. The method
includes receiving media data and information about a fixed delay
associated with the media data. The method also includes
identifying a requirement on a length of time after transmission
that the media data is passed to an application layer component or
presented to a user from the information about the fixed delay.
[0008] In yet another exemplary embodiment, an apparatus in a
sending entity in the transmission system is provided. The
apparatus includes a controller configured to identify a fixed
delay associated with transmission of media data in the
transmission system. The apparatus also includes a transmitter
configured to send information about the fixed delay as a
requirement on a length of time after transmission that the media
data is passed to an application layer component or presented to a
user of a receiving entity.
[0009] In another exemplary embodiment, an apparatus in a receiving
entity in the transmission system is provided. The apparatus
includes a receiver configured to receive media data and
information about a fixed delay associated with the media data. The
apparatus also includes a controller configured to identify a
requirement on a length of time after transmission that the media
data is passed to an application layer component or presented to a
user from the information about the fixed delay.
[0010] Before undertaking the DETAILED DESCRIPTION below, it may be
advantageous to set forth definitions of certain words and phrases
used throughout this patent document: the terms "include" and
"comprise," as well as derivatives thereof, mean inclusion without
limitation; the term "or," is inclusive, meaning and/or; the
phrases "associated with" and "associated therewith," as well as
derivatives thereof, may mean to include, be included within,
interconnect with, contain, be contained within, connect to or
with, couple to or with, be communicable with, cooperate with,
interleave, juxtapose, be proximate to, be bound to or with, have,
have a property of, or the like; and the term "controller" means
any device, system or part thereof that controls at least one
operation, such a device may be implemented in hardware, firmware
or software, or some combination of at least two of the same. It
should be noted that the functionality associated with any
particular controller may be centralized or distributed, whether
locally or remotely. Definitions for certain words and phrases are
provided throughout this patent document, those of ordinary skill
in the art should understand that in many, if not most instances,
such definitions apply to prior, as well as future uses of such
defined words and phrases.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] For a more complete understanding of the present disclosure
and its advantages, reference is now made to the following
description taken in conjunction with the accompanying drawings, in
which like reference numerals represent like parts:
[0012] FIG. 1 illustrates an example of a transmission system in
which various embodiments of the present disclosure may be
implemented;
[0013] FIG. 2 illustrates a block diagram of MMT protocol
input/output in an MMT media data transmission environment in
accordance with various embodiments of the present disclosure;
[0014] FIG. 3 illustrates a block diagram of a receiver buffer
model for simulating the receiver behavior at the sender side and
for estimating a buffer delay and size requirement in accordance
with various embodiments of the present disclosure;
[0015] FIG. 4 illustrates a timing diagram for MMTP packet
processing in the MMTP de-capsulation buffer of FIG. 3 in
accordance with various embodiments of the present disclosure;
[0016] FIG. 5 illustrates a process for operating a sending entity
in a transmission system in accordance with an illustrative
embodiment of the present disclosure;
[0017] FIG. 6 illustrates a process for operating a receiving
entity in a transmission system in accordance with an illustrative
embodiment of the present disclosure; and
[0018] FIG. 7 illustrates an example electronic device in which
various embodiments of the present disclosure may be
implemented.
DETAILED DESCRIPTION
[0019] FIGS. 1 through 7, discussed below, and the various
embodiments used to describe the principles of the present
disclosure in this patent document are by way of illustration only
and should not be construed in any way to limit the scope of the
disclosure. Those skilled in the art will understand that the
principles of the present disclosure may be implemented in any
suitably-arranged system or device.
[0020] MMT coding and media delivery is discussed in the following
document and standards description: ISO/I JTC 1/SC29/WG11, High
efficiency coding and media delivery in heterogeneous
environments--Part 1: MPEG Media Transport (MMT), July 2012, which
is hereby incorporated into the present disclosure as if fully set
forth herein. For efficient and effective delivery of coded media
data over heterogeneous IP network environments, MMT provides: a
logical model to construct a content composed of various components
for mash-up applications; the structure of data conveying
information about the coded media data for the delivery layer
processing, such as packetization and adaptation; a packetization
method and packet structure to deliver media content agnostic to a
specific type of media or coding method used over TCP or UDP,
including hybrid delivery; a format of signaling messages to manage
presentation and delivery of media content; a format of signaling
messages to manage presentation and delivery of media content; a
format of information to be exchanged across the layers to
facilitate cross layer communication.
[0021] MMT defines three functional areas including encapsulation,
delivery, and signaling. The encapsulation functional area defines
the logical structure of media content, the MMT package, and the
format data units to be processed by an MMT compliant entity. An
MMT package specifies components including media content and the
relationship among the media content to provide information needed
for adaptive delivery. The format of the data units is defined to
encapsulate the coded media to either be stored or carried as a
payload of a delivery protocol and to be easily converted between
storage and carrying. The delivery functional area defines the
application layer protocol and format of the payload. The
application layer protocol provides enhanced features, including
multiplexing, for delivery of the MMT package compared to
conventional application layer protocols for the delivery of
multimedia. The payload format is defined to carry coded media data
that is agnostic to the specific media type or encoding method. The
signaling functional area defines the format of messages to manage
delivery and consumption of MMT packages. Messages for consumption
management are used to signal the structure of the MMT package, and
messages for delivery management are used to signal the structure
of payload format and configuration of the protocol.
[0022] MMT defines a new framework for delivery of time continuous
multimedia, such as audio, video, and other static content, such as
widgets, files, etc. MMT specifies a protocol (i.e., MMTP) for the
delivery of an MMT package to a receiving entity. The MMTP signals
transmission time of the MMTP package as part of the protocol
header. This time enables the receiving entity to perform
de-jittering by examining the transmission time and reception time
of each incoming MMT packet.
[0023] Embodiments of the present disclosure recognize that
environmental conditions for receipt of media data may differ based
on the transmission path, transmission formats, and the types of
recipient devices resulting in delay between transmission and
delivery (e.g., end-to-end delay). For example, different
transmission media (e.g., wireless data communication (LTE, HSPA,
3G, WiFi, etc.), physical media (e.g., wireline, cable, Ethernet,
optical fiber, etc.) satellite broadcast, etc.) have different
associated transmission delays. Embodiments of the present
disclosure recognize that, in addition to transmission delay, other
sources may result in jitter. For example, forward error correction
(FEC) decoding may insert additional delay to enable the recovery
of lost packets, which requires receipt of sufficient source and
parity packets. Yet other sources of delay could be due to data
interleaving that may have been performed during transmission.
Embodiments of the present disclosure also recognize that recipient
device components may also impact delay. Devices, such as
computers, with larger memories and faster processing abilities may
have less delay than other devices, such as set-top boxes, with
smaller memories and slower processing abilities.
[0024] Embodiments of the present disclosure recognize that, in
certain environments, such as broadcast environments, it is
important to have a fixed end-to-end delay that each transmitted
packet experiences the same delay across a point-to-multipoint
transmission system from transmission until leaving the MMT
processing stack at the receiving entity. For example, embodiments
of the present disclosure recognize that it is important to provide
or guarantee that all clients receiving the same program present
the same content at the same time agnostic to device, protocol, or
transmission media implementation. In addition, in order to enable
hardware realization of receivers, embodiments of the present
disclosure recognize that an upper bound on the required memory
space to ensure the fixed packet delivery delay may need to be
provided. Depending on the nature of the network and the setup of
the service, MMT packets may be exposed to a wide range of jitter,
which would then result in different buffer requirements. For
example, a service that offers FEC protection on large source
blocks and which is carried over the Internet may require more
buffering than a service that is carried over a managed broadcast
and without FEC protection.
[0025] Accordingly, embodiments of the present disclosure provide a
method and apparatus to provide, enforce, and/or ensure a fixed
end-to-end delay and limited memory requirement for buffering of
incoming MMT packets. Embodiments of the present disclosure also
provide tools to signal the buffer requirement and the fixed delay
to the receiving entities.
[0026] FIG. 1 illustrates an example of a transmission system 100
in which various embodiments of the present disclosure may be
implemented. In the illustrated embodiment, the system 100 includes
a sending entity 101, a network 105, receiving entities 110-116,
wireless transmission points (e.g., an Evolved Node B (eNB), Node
B), such as base station (BS) 102, base station (BS) 103, and other
similar base stations or relay stations (not shown). Sending entity
101 is in communication with base station 102 and base station 103
via network 105 which may be, for example, the Internet, a media
broadcast network, or IP-based communication system. Receiving
entities 110-116 are in communication with sending entity 101 via
network 105 and/or base stations 102 and 103.
[0027] Base station 102 provides wireless access to network 105 to
a first plurality of receiving entities (e.g., user equipment,
mobile phone, mobile station, subscriber station) within coverage
area 120 of base station 102. The first plurality of receiving
entities includes user equipment 111, which may be located in a
small business (SB); user equipment 112, which may be located in an
enterprise (E); user equipment 113, which may be located in a WiFi
hotspot (HS); user equipment 114, which may be located in a first
residence (R); user equipment 115, which may be located in a second
residence (R); and user equipment 116, which may be a mobile device
(M), such as a cell phone, a wireless communication enabled laptop,
a wireless communication enabled PDA, a tablet computer, or the
like.
[0028] Base station 103 provides wireless access to network 105 to
a second plurality of user equipment within coverage area 125 of
base station 103. The second plurality of user equipment includes
user equipment 115 and user equipment 116. In an exemplary
embodiment, base stations 101-103 may communicate with each other
and with user equipment 111-116 using OFDM or OFDMA techniques.
[0029] While only six user equipment are depicted in FIG. 1, it is
understood that system 100 may provide wireless broadband and
network access to additional user equipment. It is noted that user
equipment 115 and user equipment 116 are located on the edges of
both coverage area 120 and coverage area 125. User equipment 115
and user equipment 116 each communicate with both base station 102
and base station 103 and may be said to be operating in handoff
mode, as known to those of skill in the art.
[0030] User equipment 111-116 may access voice, data, video, video
conferencing, and/or other broadband services via network 105. In
an exemplary embodiment, one or more of user equipment 111-116 may
be associated with an access point (AP) of a WiFi WLAN. User
equipment 116 may be any of a number of mobile devices, including a
wireless-enabled laptop computer, personal data assistant,
notebook, handheld device, or other wireless-enabled device. User
equipment 114 and 115 may be, for example, a wireless-enabled
personal computer (PC), a laptop computer, a gateway, or another
device.
[0031] FIG. 2 illustrates a block diagram of MMT protocol
input/output in an MMT media data transmission environment 200 in
accordance with various embodiments of the present disclosure. In
this illustrative example, a sending entity 205 sends media data
over a transmission medium to a receiving entity 210 according to
MMTP. The media data 215 is processed at the sending entity 205
according to MMTP. For example, the sending entity 205 may perform
MMT package encapsulation, coding, delivery, and signaling for the
media data as MMT processing units (MPUs) and MMT fragmentation
units (MFUs) 215 (e.g., fragments of an MPU). The processed media
data is then sent (e.g., as packets) to the receiving entity 210
for processing (e.g., de-capsulation, decoding, etc.) according to
MMTP. The media data processed at the receiving entity 210 is then
passed up to an upper layer programming (e.g., an application layer
program, such as a media player) as MPUs and/or MFUs for
presentation to a user completing delivery of the media data.
[0032] FIG. 3 illustrates a block diagram of a receiver buffer
model 300 for simulating the receiver behavior at the sender side
and for estimating a buffer delay and size requirement in
accordance with various embodiments of the present disclosure. In
various embodiments of the present disclosure, a sending entity
205, such as a media-delivery server (or other MMT aware node),
calculates, determines, and/or identifies a fixed end-to-end delay
for media data delivery in the point-to-multipoint transmission
system. For example, the sending entity 205 may utilize model 300
to determine effects of media data processing performed on the
packet stream on reception constraints in a receiver of a receiving
entity 210. For example, the sending entity 205 may utilize the
model to determine a required buffering delay and a required buffer
size and communicate this information to entities receiving the
media data.
[0033] In this illustrative example, the FEC decoding buffer 305 is
a model for estimating a delay and/or buffer size requirement
associated with FEC decoding. FEC decoding is typical for many
applications, where lower layer transmission may not be sufficient
to recover from channel errors or when network congestion may cause
packet drops or excessive delays. To perform FEC decoding, the
receiving entity 210 uses a buffer where incoming packets are
stored until sufficient source ("S") and repair data ("P" parity
data) is available to perform 1-EC decoding.
[0034] In this illustrative example, the sending entity 205 uses
the model of the FEC decoding buffer 305 to determine actions that
the receiving entity 210 would take regarding FEC decoding to
estimate the delay associated with FEC decoding. In other words,
the sending entity 205 uses the model of the FEC decoding buffer
305 to predict actions taken by the receiving entity 210 to
estimate FEC decoding delay. This modeling of the FEC decoding
buffer 305 by the sending entity 205 starts with the FEC decoding
buffer 305 being assumed to be initially empty. Next, for each
incoming packet i with transmission timestamp t.sub.s, the
receiving entity 210 buffers the packet i using the FEC decoding
buffer 305, if buffer_occupancy+packet_size<max_buffer_size.
Otherwise, the receiving entity 210 discards packet i as being
non-conformant with the buffer model. The receiving entity 210 then
determines if FEC is applied to packet i. If FEC is applied to
packet i, the receiving entity 210 determines source block j to
which packet i belongs, determine the insertion time t of a first
packet of source block j, at time t+FEC_buffer_time moves all
packets (after FEC correction, if needed) of source block j to the
de-jitter buffer, and discards the repair packets. The sending
entity 205 utilizes the FEC_buffer_time as the required buffer time
for FEC decoding from the reception of the first packet of a source
block and until FEC decoding is attempted. This time is typically
calculated based on the FEC block size.
[0035] The de jitter buffer 310 is a model used by the sending
entity to estimate a delay and/or buffer size requirement
associated with de-jittering of packets, i.e. removal of the delay
jitter of packets. The de-jitter buffer ultimately ensures that
MMTP packets experience a fixed transmission delay from source to
the output of the MMTP protocol stack, assuming a maximum
transmission delay. The receiving entity 210 may discard data units
that experience a transmission delay larger than the maximum
transmission delay as being very late.
[0036] This modeling of the de-jitter buffer 310 by the sending
entity 205 starts with the de-jitter buffer being assumed to be
initially empty. The receiving entity 210 then inserts an MMTP
packet in the de-jitter buffer 310 as the packet arrives. The
receiving entity 210 then removes the MMTP packet at time
t.sub.s+.DELTA., where t.sub.s is the transmission timestamp of the
MMTP packet and .DELTA. is the fixed end-to-end delay that is
signaled for the media data. After the de-jittering is applied, all
MMTP packets that arrived correctly (or were recovered through
FEC/retransmissions) will have experienced the same end-to-end
delay.
[0037] The MMTP de-capsulation buffer 315 is a model used by the
sending entity to estimate a delay and/or buffer size requirement
associated with MMTP processing before passing the output to the
upper layers. The output of the MMTP processor may either be the
MFU payload (in low-delay operation), a complete movie fragment, or
a complete MPU. MPUs may be fragmented into smaller packets or
aggregated into larger packets, depending on their size. The
de-capsulation (removal of the MMTP packet and payload headers) and
any required de-fragmentation/de-aggregation of the packets is then
performed as part of the MMTP processing. This procedure may
require some buffering delay, called de-capsulation delay, to
perform assembly when an MPU is fragmented into multiple MMTP
packets. However, in this illustrative embodiment, de-capsulation
delay may not be considered as part of the fixed end-to-end delay,
and the availability of an MPU for consumption by the coded media
layer can be guaranteed by the entity fragmenting the MPU into
multiple MMTP packets, regardless of the de-capsulation delay.
[0038] FIG. 4 illustrates a timing diagram 400 for MMTP packet
processing in the MMTP de-capsulation buffer 315 in accordance with
various embodiments of the present disclosure. The timing diagram
400 is an example of a buffer level in the MMTP de-capsulation
buffer 315 over time as MMTP packets are processed and output to
upper layers. For example, the timing diagram 400 is an
illustration of estimating the buffer requirement associated with
MMTP packet processing.
[0039] The modeling of the MMTP de-capsulation buffer 315 by the
sending entity 205 starts with the MMTP de-capsulation buffer
assumed as initially empty. The receiving entity 210 inserts an
MMTP packet into the MMTP de-capsulation buffer 315 after the
de-jittering is performed. For MMTP packets carrying aggregated
payload, the receiving entity 210 removes the packet and payload
header and splits the aggregate into separate MPUs. For MMTP
packets carrying fragmented payload, the receiving entity 210 keeps
the packet in the MMTP de-capsulation buffer 315 until all
corresponding fragments are received correctly or until a packet is
received that does not belong to the same fragmented MPU. If all
fragments of an MPU are received (e.g., at time 405 or time 410),
the receiving entity 210 removes the MMTP packet and payload
header, reassembles, and forwards the reconstructed MPU to the
upper layer. Otherwise, if some fragments of the MPU are not
received, the receiving entity 210 may discard fragments of the
non-complete MPU.
[0040] Based on this receiver buffer model 300, the sending entity
205 is able to determine the transmission schedule, the buffer size
and the buffering delay .DELTA., reduce and/or ensure that no
packets are dropped, assuming a maximum delivery delay in the
target path. The sending entity 205 provides and/or guarantees
packets that experience a transmission delay below a set threshold
will be output to the upper layer after a constant delay across the
point-to-multipoint transmission system and without causing the
client buffer to underflow or overflow.
[0041] After determining the required buffer size and the fixed
end-to-end delay for the media data, the sending entity 205
communicates this information to the receiving entity 210. For
example, the sending entity 205 may communicate this information to
the receiving entity 210 using a signaling protocol between the
sending and receiving entities. In various embodiments, the sending
entity 205 may continuously run the receiver buffer model 300 to
verify that the selected end-to-end delay and buffer size are
aligned and do not cause buffer under-runs or overruns. At the
receiver side, the signaling of the fixed delay instructs the
receiving entity 210 to perform buffering so that each data unit
experiences the signaled fixed end-to-end delay .DELTA. before the
data unit is forwarded to upper layers. Under the assumption that
clocks between the sending and receiving entities are synchronized,
the receiving entity 210 can calculate the output time of the data
based on the transmission timestamp and the signaled fixed
end-to-end delay.
[0042] In some embodiments, sending entity 205 performs the
signaling using, a session description file, such as a session
description protocol (SDP) file. In an SDP, a media session is
described that is delivered using the MMTP protocol. The media
session includes the fixed end-to-end delay and/or the required
buffer size. Table 1 below illustrates one example of a media
session description of an SDP file that signals the fixed
end-to-end delay and the buffer size requirement.
TABLE-US-00001 TABLE 1 m=asset 23442 UDP/MMTP 1 a=assetid:1 MP4
a=min-buffer-size: 1000000 a=end-to-end-delay: 2500
[0043] In another embodiment, the signaling of the fixed end-to-end
delay and the buffer size requirement is performed using the MMTP
Signaling Function. In such embodiment, a new signaling message is
devised to carry the above information.
[0044] In this example, the buffer size is given in bytes, and the
fixed end-to-end delay is given in milliseconds. In other
embodiments, sending entity 205 may perform the signaling using
MMTP signaling messages, where either a special signaling message
type is defined or the information is included in an existing
signaling message.
[0045] In determining the fixed delay, the sending entity 205
estimates the maximum expected and tolerable transmission delay in
the transmission path down to the receivers. If NEC is in use, the
sending entity 205 adds an FEC buffering delay that covers for the
time needed to assemble a source block (e.g., FEC_buffer_time
discussed above), in the situation that FEC decoding is required to
recover lost MMTP packets. Additionally, the sending entity 205
adds any delays that might be incurred by fragmentation of packets.
The sending entity 205 signals the resulting estimation of the MMTP
delivery delay as the fixed end-to-end delay. One example of
estimating the fixed end-to-end delay is provided by Equation 1
below:
fixed end-to-end delay=maximum transmission delay+FEC_buffer_time
[Equation 1]
[0046] In various embodiments, to estimate the resulting buffer
requirement, the sending entity 205 may use the fixed end-to-end
delay and subtract the minimum transmission delay for the
transmission path down to the receiver as an estimated maximum
amount of time that the data would need to be buffered by the
sending entity 205. The sending entity 205 may then estimate the
buffer size requirement as the maximum bitrate of the MMTP stream
multiplied by the calculated buffered data duration. One example of
estimating the fixed end-to-end delay is provided by Equation 2
below:
buffer size=(maximum delay-minimum delay)*maximum bitrate [Equation
2]
[0047] While various embodiments described herein discuss MMT data
communication, it is noted that the various embodiments of the
present disclosure are not limited to MMT communications. For
example, the fixed delay and buffer size determinations may be
applied to any suitable type of data or media content delivery
and/or any suitable type of transmission system in accordance with
the principals of the present disclosure.
[0048] FIG. 5 illustrates a process for operating a sending entity
in a transmission system in accordance with an illustrative
embodiment of the present disclosure. For example, the process
depicted in FIG. 5 may be performed by the sending entity 205 in
FIG. 2. The process may also be implemented by the sending entity
101 in FIG. 1.
[0049] The process begins with the sending entity identifying a
fixed delay associated with transmission of media data (step 505).
For example, in step 505, the sending entity may be a media server
in a point-to-multipoint transmission system that delivers
time-sensitive content to a variety of devices and over a variety
of communication mediums. To identify this delay, the sending
entity may estimate the delay or identify a pre-calculated or
standardized delay from another source. In one example, the sending
entity may estimate a transmission delay associated with a
transmission path (e.g., wireless, Ethernet, satellite broadcast,
etc.) from the sending entity to one or more receiving entities in
the multi-point transmission system. For example, the transmission
delay may be an estimate of a maximum transmission delay based on
transmission media and device types associated with each of the
receiving entities in the multi-point transmission system. The
sending entity may also estimate a buffering delay associated with
processing received packets for the media data in the receiving
entity. The sending entity may then calculate the fixed delay based
on the transmission delay and the buffering delay.
[0050] The sending entity then determines a buffer size requirement
for a receiving entity (step 510). For example, in step 510, the
sending entity may determine the expected amount of time that the
data needs to be buffered by the receiving entity as the fixed
delay minus the minimum transmission delay. The sending entity may
then calculate the buffer size requirement based on this amount of
buffering time and a bitrate associated with the media data.
[0051] Thereafter, the sending entity sends information about the
fixed delay and the buffer size requirement (step 515). For
example, in step 515, the sending entity may signal the buffer size
requirement in a message separate from sending the media data or in
metadata preceding or accompanying the transmission of the media
data. In these examples, the fixed delay is a requirement of a
length of time after transmission that the media data is presented
to a user of a receiving entity. In other words, the fixed delay is
a time after which the sending entity is permitted to pass the
media data up to an upper layer program for the ultimate
presentation of the media data to the user. In these examples, the
sending entity provides and/or ensures that media data is displayed
at about the exact same time regardless of transmission media or
recipient device type among the multiple recipient devices that may
be present in a point-to-multipoint transmission environment.
[0052] FIG. 6 illustrates a process for operating a receiving
entity in a transmission system in accordance with an illustrative
embodiment of the present disclosure. For example, the process
depicted in FIG. 6 may be performed by the receiving entity 210 in
FIG. 2. The process may also be implemented by the receiving entity
110 in FIG. 1.
[0053] The process begins with the receiving entity receiving media
data and information about a fixed delay associated with the media
data (step 605). For example, in step 605, the receiving entity may
receive this information with or in advance of the media data.
[0054] The receiving entity then identifies a requirement on a
length of time after transmission that the media data is presented
to a user (step 610). For example, in step 610, the receiving
entity may use the fixed delay as a length of time to determine
when to pass received media data to an upper layer for ultimate
presentation to the user.
[0055] Thereafter, the receiving entity stores received data
associated with the media data in a buffer (step 615). For example,
in step 615, the receiving entity may store the media data upon
receipt until a time from a transmission timestamp associated with
the received data plus the fixed delay has elapsed. The receiving
entity then determines whether a present time is the transmission
timestamp plus the fixed delay (step 620). If the present time is
less than the transmission timestamp plus the fixed delay, the
sending entity continues to buffer the media data for later
presentation and delivery. If the present time is greater than the
transmission timestamp plus the fixed delay, the sending entity may
discard the data as being received too late.
[0056] If, however, the present time is the transmission timestamp
plus the fixed delay, the receiving entity provides the received
data to the user via a user interface (step 625), with the process
terminating thereafter. For example, in step 625, the receiving
entity may pass the media data to an application layer program for
presentation of the media data to the user. In these examples, the
receiving entity identifies and complies with the fixed delay for
the media data to ensure that media data is displayed at the
receiving entity at about the exact same time among the other
receiving entities that may be present in a point-to-multipoint
transmission environment.
[0057] Although FIGS. 5 and 6 illustrate examples of processes for
sending and receiving entities in a transmission system,
respectively, various changes could be made to FIGS. 5 and 6. For
example, while shown as a series of steps, various steps in each
figure could overlap, occur in parallel, occur in a different
order, or occur multiple times.
[0058] FIG. 7 illustrates an example electronic device 700 in which
various embodiments of the present disclosure may be implemented.
In this example, the electronic device 700 includes a controller
704, a memory 706, a persistent storage 708, a communication unit
710, an input/output (I/O) unit 712, and a display 714. In these
illustrative examples, electronic device 700 is an example of one
implementation of the sending entity 101 and/or the receiving
entities 110-116 in FIG. 1. Electronic device 700 is also one
example of the sending entity 205 and/or the receiving entity 210
in FIG. 2.
[0059] Controller 704 is any device, system, or part thereof that
controls at least one operation. Such a device may be implemented
in hardware, firmware, or software, or some combination of at least
two of the same. For example, the controller 704 may include a
hardware processing unit and/or software program configured to
control operations of the electronic device 700. For example,
controller 704 processes instructions for software that may be
loaded into memory 706. Controller 704 may include a number of
processors, a multi-processor core, or some other type of
processor, depending on the particular implementation. Further,
controller 704 may be implemented using a number of heterogeneous
processor systems in which a main processor is present with
secondary processors on a single chip. As another illustrative
example, controller 704 may include a symmetric multi-processor
system containing multiple processors of the same type.
[0060] Memory 706 and persistent storage 708 are examples of
storage devices 716. A storage device is any piece of hardware that
is capable of storing information, such as, for example, without
limitation, data, program code in functional form, and/or other
suitable information either on a temporary basis and/or a permanent
basis. Memory 706, in these examples, may be, for example, a random
access memory or any other suitable volatile or non-volatile
storage device. For example, persistent storage 708 may contain one
or more components or devices. Persistent storage 708 may be a hard
drive, a flash memory, an optical disk, or some combination of the
above. The media used by persistent storage 708 also may be
removable. For example, a removable hard drive may be used for
persistent storage 708.
[0061] Communication unit 710 provides for communications with
other data processing systems or devices. In these examples,
communication unit 710 may include a wireless (cellular, WiFi,
etc.) transmitter, receiver and/or transmitter, a network interface
card, and/or any other suitable hardware for sending and/or
receiving communications over a physical or wireless communications
medium. Communication unit 710 may provide communications through
the use of either or both physical and wireless communications
links.
[0062] Input/output unit 712 allows for input and output of data
with other devices that may be connected to or a part of the
electronic device 700. For example, input/output unit 712 may
include a touch panel to receive touch user inputs, a microphone to
receive audio inputs, a speaker to provide audio outputs, and/or a
motor to provide haptic outputs. Input/output unit 712 is one
example of a user interface for providing and delivering media data
(e.g., audio data) to a user of the electronic device 700. In
another example, input/output unit 712 may provide a connection for
user input through a keyboard, a mouse, external speaker, external
microphone, and/or some other suitable input/output device.
Further, input/output unit 712 may send output to a printer.
Display 714 provides a mechanism to display information to a user
and is one example of a user interface for providing and delivering
media data (e.g., image and/or video data) to a user of the
electronic device 700.
[0063] Program code for an operating system, applications, or other
programs may be located in storage devices 716, which are in
communication with the controller 704. In some embodiments, the
program code is in a functional form on the persistent storage 708.
These instructions may be loaded into memory 706 for processing by
controller 704. The processes of the different embodiments may be
performed by controller 704 using computer-implemented
instructions, which may be located in memory 706. For example,
controller 704 may perform processes for one or more of the modules
and/or devices described above.
[0064] In some embodiments, various functions described above are
implemented or supported by a computer program product that is
formed from computer-readable program code and that is embodied in
a computer-readable medium. Program code for the computer program
product may be located in a functional form on a computer-readable
storage device that is selectively removable and may be loaded onto
or transferred to electronic device 700 for processing by
controller 704. In some illustrative embodiments, the program code
may be downloaded over a network to persistent storage 708 from
another device or data processing system for use within electronic
device 700. For instance, program code stored in a
computer-readable storage medium in a server data processing system
may be downloaded over a network from the server to electronic
device 700. The data processing system providing program code may
be a server computer, a client computer, or some other device
capable of storing and transmitting program code.
[0065] Embodiments of the present disclosure recognize that MMTP
has been developed to improve upon and replace existing transport
protocols by providing a generic protocol, suitable for the
delivery of media data. MMTP addresses delay tolerant applications
as well as real-time low-delay applications, such as live
streaming. In order to ensure that the MMTP protocol operates
consistently across receivers and that the needed buffer space is
made available by the clients, embodiments of the present
disclosure provide methods and apparatuses to determine the
end-to-end delay, to estimate the required buffer space, and signal
this information to the receiver. This functionality is especially
important for broadcast receivers where the receiving client is
implemented in hardware (e.g. a set-top box).
[0066] Although the present disclosure has been described with an
exemplary embodiment, various changes and modifications may be
suggested to one skilled in the art. It is intended that the
present disclosure encompass such changes and modifications as fall
within the scope of the appended claims.
* * * * *